Internal mold release agents used in the production of molded polyurethane and polyurea products are known. U.S. Pat. Nos. 4,201,847 and 4,254,228 describe an internal mold release which is the reaction product of an organic polyisocyanate and an active hydrogen containing fatty acid ester. U.S. Pat. No. 4,111,861 describes four different classes of internal mold releases; i) mixtures of aliphatic or aryl carboxylic acid and a polar metal compound; ii) carboxyalkylsiloxanes; iii) aliphatic glyoximes; and iv) aralkyl ammonium salts. Other known release agents include salts of acids (such as oleic acid) and primary amines (see, U.S. Pat. No. 3,726,952), reaction products of long chain fatty acids and ricinoleic acid (see, U.S. Pat. No. 4,058,492), and salts of acids (such as oleic acid) and tertiary amines (see, U.S. Pat. No. 4,098,731).
Zinc carboxylates containing from 8 to 24 carbon atoms per carboxylate group have also been described (U.S. Pat. Nos. 4,519,965, 4,581,386, 4,585,803 and 4,764,537, and British Patent 2,101,140). Release agents containing zinc carboxylates in combination with primary or secondary amine compatibilizers and an organic material containing a carboxylic acid group, a phosphorous containing acid group or a boron containing acid group, are described and published European Patent Application 0,119,471.
Recently, a system which provides release from a bare metal mold has been developed. The system utilizes the reaction product of an organic polyisocyanate and an active hydrogen containing fatty acid ester in the A-side and a zinc carboxylate in the B-side (see, U.S. Pat. No. 4,868,224). One problem with this system is that the zinc carboxylate/solubilizer combination catalyzes the hydroxyl/isocyanate reaction. This makes the system relatively fast, leading to difficulties in filling large molds. It is known to add fatty acids to polyurea systems in order to increase the green strength and aid in mold release (see, U.S. Pat. No. 4,499,254). Another known system which releases from bare metal molds is disclosed in U.S. Pat. No. 5,019,317. It uses a similar isocyanate/fatty acid ester reaction product and zinc carboxylate combination as described hereinabove to produce a molded product.
U.S. Pat. No. 3,875,069 discloses lubricant compositions which are said to be useful in the shaping of thermoplastic materials. These lubricant materials comprise (A) mixed esters with hydroxyl and acid numbers of 0 to 6 of (a) alkane polyols, (b) a dicarboxylic acid, and (c) aliphatic hydrocarbon monocarboxylic acids, said mixed esters having a molecular weight of at least 524; and (B) esters selected from the group consisting of (1) esters of the dicarboxylic acids of (A)(b) and aliphatic monofunctional alcohols, (2) esters of aliphatic monofunctional alcohols and aliphatic hydrocarbon monocarboxylic acids, and (3) complete esters or partial esters of alkanepolyols and aliphatic hydrocarbon monocarboxylic acids, with the ratio by weight of (A) to (B) being from 1:3 to 9:1.
The present invention is directed to a new internal mold release agent which provides excellent release from metal molds.